Process for banana ripening



United States Patent O 3,234,028 PROCESS FOR BANANA RIPENING Milton L.Dunham, Jr., Tonawanda, and Francis M. OConnor, Kenmore, N.Y., assignorsto Union Carbide Corporation, a corporation of New York No Drawing.Continuation of application Ser. No. 631,398, Dec. 31, 1956. Thisapplication Sept. 20, 1961, Ser. No. 139,370

2 Claims. (Cl. 99-103) This application is a continuation of copendingapplication Serial No. 631,398, filed December 31, 1956, now abandoned.

This invention relates to agents for use in chemical reactions andprocesses for their use. More particularly the invention relates toagents from which materials can be released at an appropriate time toact as reactants or catalysts in chemical reactions. The agents of theinvention may be used as carriers of aromas, defoliants,pharmaceuticals, and bleaching agents for example.

It is an object of the present invention to provide an agent whichcontains materials that are to participate in or promote a chemicalreaction and which retains these materials until their release isdesired. 7

The objects of the invention are accomplished by adsorbing theappropriate material with a zeolitic molecular sieve. The resultingagent may be blended with other materials and their release controlledwith the beneficial results which will appear from the examples andtests described below.

Zeolitic moleucular sieves, both natural and synthetic, aremetal-a1uminum-silicates. The crystalline structure of these materialsis such that a relatively large sorption area is present inside eachcrystal. Access to this area is by way of openings or pores in thecrystal. Molecules are selectively adsorbed by molecular sieves on thebasis of size and polarity among other things.

To facilitate an understanding of the terms used in the examples andclaims appearing below, some of the synthetic zeolitic molecular sievesused in making the curing agent of the invention will be described. Forconvenience one of the synthetic molecular sieves used has beendesignated zeolite X and is described, together with a process formaking it, in detail in United States patent applicat-ion Serial No.400,389, filed December 24, 1953, now US. Patent No. 2,882,244.

The general formula for zeolite X, expressed in terms of mol fractionsof oxides is as follows:

0.9:0.2M ,,O:A1 O 22.510.5Si 20 to 8 H O In the formula M represents ametal and 12 its valence. The zeolite is activated or made capable ofadsorbing certain molecules by the removal of water from the crystal asby heating. Thus the actual number of mols of water present in thecrystal will depend upon the degree of dehydration or activation of thecrystal.

The metal represented in the formula above by the letter M can bechanged by conventional ion exchange techniques. The sodium form of thezeolite, designated sodium zeolite X, is the most convenient tomanufacture. For this reason the other forms of zeolite X are usuallyobtained by the modification of sodium zeolite X.

A typical formula for sodium zeolite X is After activation by heating atleast some of the water is removed from the zeolite X and it is thenready for use in preparing the agents of the invention.

The major lines in the X-ray diffraction pattern of sodium zeolite X areset forth in Table A below.

TABLE A d Value of reflection in A.: [/1 14.42i02 100 8.82:0.1 18

In obtaining the X-ray diffraction powder patterns, standard techniqueswere employed. The radiation was the K doublet of copper, and a Geigercounter spectrometer with a strip chart pen recorder was used. The peakheights, I, and 'the positions as a function of 20, Where 0 is the Braggangle, were read from the spectrometer chart. From these, d (obs), theinterplanar spacing in A., corresponding to the recorded lines wascalculated. The X-ray patterns indicate a cubic unit cell of dimensionsbetween 24.5 A. and 25.5 A.

To make sodium zeolite X reactants are mixed in aqueous solution andheld at about 100 C. until the crystals of zeolite X are formed.Preferably the reactants should be such that in the solution thefollowing ratios prevail:

SiO A1 0 3-5 Na O/SiO H O/Na O 35-60 The manner in which zeolite X mightbe obtained is illustrated by the following: 10 grams of NaAlO 32 gramsof an aqueous solution containing by weight about 20% N320 and 32% S105.5 grams of NaOH and cc. H O were mixed and held in an autoclave for 47hours at about 100 C. Crystalline zeolite X was recovered by filteringthe reacted materials and washed with water until the pH of the effluentwash water is between 9. and 12'. The crystals are dried after whichthey are ready for use in making the agent of the invention.

Another synthetic Zeolitic molecular sieve which has been successfullyused in the practice of this invention has been designated zeolite A andis described in detail together with processes for its preparation inUnited States patent application Serial No. 400,388, filed December 24,1953, now US. Patent No. 2,882,243.

The general formula for zeolite A, expressed in terms of mol fractionsof oxides is as follows:

1.0:02 M O:Al O :l.85i0.5 $10 20 to 6 H O In the formula M represents ametal, hydrogen, or ammonium, n the valence of M. The amount of H 0present in zeolite A will of course depend on the degree of dehydrationof the crystals.

As in the case of zeolite X and other zeolites, the element or groupdesignated by M in the formula can be changed by conventional ionexchange techniques. Sodium zeolite A is the most convenient form toprepare and other forms are usually obtained from it by an exchange ofions in aqueous solutions. 7 A typical formula for sodium zeolite A isNa O:1.0 A1203IL85 810215.]. H2O

The removal of at least part of the water, as by heating,

would be sufiicient to prepare the sodium zeolite A for.

use in making the agent of the invention.

Using the techniques by which the X-ray diffraction data for sodiumzeolite X was obtained, similar data forsodium zeolite A was obtainedand is recorded in TableB.

TABLE B To make sodium zeolite A reactants are mixed in aque-: oussolution and held at about 100 C. until crystals of sodium'zeolite A areformed. The reactants should be such that in the solution the followingratios prevail:

SiO /Al O 1.3-2.5 Na O/SiO 0.8-3.0 H O/Na O 35,-200

An example of the mannerin which zeolite A may beprepared is as follows:80 grams of NaAlO 126 grams of an aqueous solution of sodium silicatecontaining about 7.5% by weight Na O and 25.8% by weight SiO and 320cubic centimeters of H 0 were placed in an autoclave; In the autoclavethe following ratios prevailedzz SiO /Al O 1.2; Na 0/SiO 1.2; and H O/Nao, 36. The contents of the autoclave were held at about 100 C. for about12 hours.

effluent wash water had a pH of between 9 and 12. After drying anddehydration the crystals are ready for use in making the agents of theinvention.

The manner in which the agents of the invention may be made and used canbe seen from the following examples.

Example I Ethylene is known to effect. the defoliation of cotton plants.Difliculties are experienced in applying 611131161165 to the plants. Theproblem can be solved with the agents of: the invention.

A sample of. sodium zeolite A was dehydrated. and z:

ethylene was introduced .into a chamber containing the. dehydratedzeolite. Ethylene was adsorbed by the zeolite. Cotton plants were placedunder a jar with one:

gram of the sample which contained 6.8 weight-percent adsorbed ethylene.The plant was completely defoliatedin four days indicating gradual andeffective release ofv the ethylene.

Ethylene-is known to be efiective as a ripening agent 1 for bananas. Thecontrol of this ripening process can be improved by using the agents ofthe invention as will be seen in Example II.

. Example H,

Green bananas were placed in polyethylene bags, which Crystallinezeolite A was recovered by filtration and washed with distilled wateruntil. they The controlled Because molecular sieves will adsorb vaporsand retain them for long periods of time or until released by heating orotherwise, the molecular sieves are useful in retaining aromas untilztheirrelease is desired. In Example III the adsorption and release ofan aroma with a number of'molecular sieves and the release of the aromaby a number of means are described.

Example vIII- Pellets of sodium zeolite A, pellets of calcium zeolite Aand pellets of sodium zeolite X were each activated and subjected to astream of gases carrying the aroma emitted from roasted coffee grounds.Samples of each type of pellet were then held in a stream of carbondioxide. The carbon dioxide was adsorbed by the molecular sievesreleasing the coffee aroma in :each instance: Similar results wereobtained when moist air was passed over the aroma laden crystals.

The use of molecular sieves to hold aromasuntil their a release isdesired can of course be employed in products other than coffee. Forexample, the presence of-molecu-.

lar sieves,-laden with they aroma of cooked food, can be 1 Perfume orthe likeadsorbed by theimolecular :sieves can be :placed in soap whereit, will 'be released=when the.

advantageously added to dehydrated food products.

soap:and the -molecular :sieve .are wetted. Similarly, a perfume oraroma in armolecular sieve can be-released by the burning of a waxcandle which contains the treated molecular sieve.

Pharmaceutical agents can be .adsorbed on molecular sieves and theirapplication and effectiveness improved. Agentswhich have a germicidaleffect on bacteria .causing .athletes foot can. be adsorbed. by.t'nemolecular sieve and dusted over the infected skin area. Aswthesieve adsorbs moisture from the body, the germicidal agent is-released.In addition tosupplying a germicide. the preparationtends to effect thedrying of the skin. This drying actionsmight also be used in thetreatment of .burns. Fumigants such as hydrogen sulfide can be adsorbedand. released slowly where and when'needed by the application ofmoisture to the molecular sieve.

The adsorptivecapacity of thewmolecular sieves for bleachingagents,-such as chlorine and hydrogen peroxide, make them useful in thebleaching .of many materials, for example paper, where moisture ispresent to desorb the bleaching agent. i

These examples of the use of the agents'ofthe invention serve toillustrate the manner' in whichthey might be .used.v Molecular sievesother than those mentioned in the specification may be satisfactorilyemployed within the scope of the invention. Chabazite, mordenite andfaujasite are examples of naturally occurring molecular sievesthatperforrn satisfactorily in the practicehof the invention. 1

What is claimed. is:

1. A process for banana ripening comprising the steps of adsorbingethylene on an unreactive dehydrated crystal line zeolitic molecularsieve, contacting the ethylene-containing molecularsievewithJmoisture-containing air in the immediate proximity of saidbanana thereby displac+ ing and controllably releasingsaid ethylene fromsaid molecular sieve for contact with and ripening of said banana.

' 2. A process according to claim 1 in which zeolite A is Psaidcrystalline zeolitic molecular sieve.

References Cited by theiExamin'er UNITED STATES PATENTS 1,421,743 7/1922Stuer et al. 23.112 X- 2,040,811 5/1936 Nikitin et al.i' 23-113 X'2,245,867 6/ 1941 Mehrlich. 2,429,981 11/1947 Bates 23l12 X 2,882,2434/1959 Milton... 23ll3 (Other. references on following page) 5 6 UNITEDSTATES PATENTS Lynch: Chemical Abstracts, vol. 31, col. 2258(9) to 22591937 2,970,889 2/1961 Ishmo 23113 X I 2,971,904 2/1961 Gladrow et a1.19glgelson. Chemical Abstracts, vol. 33, col. 5888(1), 2,988,577 6/1961Sensel 23112 X 3,036,980 5/1962 Dunham et a1 260*314 5 19ggelrger inChemical Abstracts, vol. 42, col. 5954(d),

OTHER REFERENCES Ahlgren et al.: Principles of Weed Control, I. WileyLEWIS GOTTS Primary Examiner & Sons, New York, 1951, page 272. MAURICEA. BRINDISI, IRVING MARCUS,

Jones: Chemical Abstracts, vol. 35, col. 2994(1), 1941. 10 Examiners.

1. A PROCESS FOR BANANA RIPENING COMPRISING THE STEPS OF ADSORBINGETHYLENE ON AN UNREACTIVE DEHYDRATED CRYSTALLINE ZIOLITIC MOLECULARSIEVE, CONTACTING THE ETHYLENE-CON TAINING MOLECULAR SIEVE WITHMOISTURE-CONTAINING AIR IN THE IMMEDIATE PROXIMITY OF SAID BANANATHEREBY DISPLACING AND CONTROLLABLY RELEASING SAID ETHYLENE FROM SAIDMOLECULAR SIEVE FOR CONTACT WITH AND RIPENING OF SAID BANANA.